相关论文: The Binary Black Hole Merger Rate from Ultralumino…
A sub-set of the brightest ultraluminous X-ray sources (ULXs), with X-ray luminosities well above $10^{40}$ erg s$^{-1}$, typically have energy spectra which can be well described as hard power-laws, and short-term variability in excess of…
An ultraluminous X-ray source (ULX) in NGC 5252 has been known as a strong candidate for an off-nuclear intermediate-mass black hole. We present near-infrared imaging data of the ULX obtained with the William Herschel Telescope. Using this…
General relativistic magnetohydrodynamic (GRMHD) simulations have been instrumental in our understanding of high energy astrophysical phenomena over the past two decades. Their robustness and modularity make them a great tool for…
In our recent work, we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes, could be reliably extended to estimate the mass of supermassive black holes accreting at moderate to high level. Here, we…
We report the discovery of a spectroscopically confirmed z = 1.824 minor merger with a mass ratio of ~35:1 in which the secondary (smaller) galaxy hosts a luminous AGN. The system is identified in the 3D-HST survey and exhibits clear tidal…
A new, transient ultraluminous X-ray source (ULX) was recently discovered by Chandra in M31 with a luminosity at ~ 5 x 10^39 erg/s. Here we analyse a series of five subsequent XMM-Newton observations. The steady decline in X-ray luminosity…
We perform a search for binary black hole mergers with one subsolar mass black hole and a primary component above $2 M_\odot$ in the second observing run of LIGO/Virgo. Our analysis therefore extends previous searches into a mass region…
The Ultra Luminous X-ray (ULX) source HLX-1 in the galaxy ESO 243-49 has an observed maximum unabsorbed X-ray luminosity of 1.3e42 erg/s (0.2-10.0 keV). From the conservative assumption that this value exceeds the Eddington limit by at most…
Ultraluminous X-ray sources (ULXs) were identified as a separate class of objects in 2000 based on data from the Chandra X-Ray Observatory. These are unique objects: their X-ray luminosities exceed the Eddington limit for a typical…
We derive the luminosity-temperature relation for the super-critically accreting black holes (BHs) and compare it to the data on ultraluminous X-ray sources (ULXs). At super-Eddington accretion rates, an outflow forms within the…
A puzzling class of exotic objects, which have been known about for more than 30 years, is reaching a new era of understanding. We have discovered hundreds of Ultra Luminous X-ray sources (ULXs) - non-nuclear sources with X-ray luminosity…
We present general relativistic radiation MHD simulations of super-Eddington accretion on a $10M_\odot$ black hole. We consider a range of mass accretion rates, black hole spins, and magnetic field configurations. We compute the spectra and…
Ultra-Luminous X-ray sources (ULXs) are accreting black holes for which their X-ray properties have been seen to be different to the case of stellar-mass black hole binaries. For most of the cases their intrinsic energy spectra are well…
The discovery of pulsations in several Ultraluminous X-ray sources (ULXs) demonstrated that a fraction of ULXs are powered by super-Eddington accretion onto neutron stars (NSs). This opened the debate as to what is the NS to black hole (BH)…
The origin of rare and elusive ultramassive black holes (UMBH, with MBH > 1e10 Msun) is an open question. Using the large volume cosmological hydrodynamic simulation ASTRID, we report on the formation of an extremely massive UMBH with MBH ~…
The black hole mass and accretion rate in Ultraluminous X-ray sources (ULXs) in external galaxies, whose X-ray luminosities exceed those of the brightest black holes in our Galaxy by hundreds and thousands of times$^{1,2}$, is an unsolved…
We investigate the relationship between the hard X-ray photon index $\Gamma$ and the Eddington ratio ($\xi=L_{X}(0.5-25 \rm keV)/L_{Edd}$) in six X-ray binaries (XRBs) with well constrained black hole masses and distances. We find that…
Ultraluminous X-ray sources (ULXs) were an enigma since their discovery. ASCA showed that they are accreting black holes (BHs) with unknown mass, while Chandra & XMM data shows that the many of the lower luminosity ULXs can be explained by…
An open question remains whether Ultraluminous X-ray Sources (ULXs) really contain intermediate-mass black holes (IMBHs). We carefully investigated the XMM-Newton EPIC spectra of the four ULXs that were claimed to be strong candidates of…
Cool thermal emission components have recently been revealed in the X-ray spectra of a small number of ultra-luminous X-ray (ULX) sources with L_X > 1 E+40 erg/s in nearby galaxies. These components can be well fitted with accretion disk…